Confidence Interval Help!

A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on a very accurate scale. The results in grams were3.0873.1313.2413.2413.2703.3533.4003.4113.4373.477 (a) Construct a 90 percent confidence interval for the true mean weight. (b) What sample size would be necessary to estimate the true weight with an error of ± 0.03 grams with 90 percent confidence?

This is what I got so far? Im lost! 3.3115 ± 1.645 (0.131988888)/√10 =

A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on a very accurate scale. The results in grams were3.0873.1313.2413.2413.2703.3533.4003.4113.4373.477 (a) Construct a 90 percent confidence interval for the true mean weight. (b) What sample size would be necessary to estimate the true weight with an error of ± 0.03 grams with 90 percent confidence?

This is what I got so far? Im lost! 3.3115 ± 1.645 (0.131988888)/√10 =